Method and system for aligning a vehicle with an artificial horizon

ABSTRACT

A method and system for positioning a vehicle chassis in approximate alignment with a predetermined datum are provided. The vehicle includes a first longitudinal end adapted to be pivotally connected to a substantially fixed point and a second longitudinal end including at least one axle and an operatively associated two-corner fluid suspension system. According to the method, the fluid suspension system controls the alignment of the vehicle chassis to be aligned with an artificial horizon represented as the predetermined datum.

This application is a continuation-in-part of U.S. patent application Ser. No. 12/034,351, filed on Feb. 20, 2008, which is a continuation of U.S. patent application Ser. No. 11/494,935, filed on Jul. 28, 2006, now U.S. Pat. No. 7,357,397, which is a continuation of U.S. patent application Ser. No. 10/513,734, filed on Nov. 4, 2004, now U.S. Pat. No. 7,104,547, which was the National Stage of International Application No. PCT/US2004/011615, filed Apr. 16, 2004, which claims the benefit of priority from U.S. Provisional Patent Application No. 60/463,487, filed on Apr. 17, 2003, each of which is hereby incorporated herein by reference in its entirety.

BACKGROUND

The present disclosure broadly relates to air suspension systems and, more particularly, an electronically controlled air suspension system for use in association with a stationary vehicle that adjusts the air springs of the stationary vehicle to place the vehicle chassis thereof in substantial alignment with an artificial horizon or other predetermined datum.

The present disclosure finds particular application in association with the use of larger mobile vehicles, such as recreational vehicles (RVs), travel trailers and over-the-road truck trailers, for example, and will be described herein with particular reference thereto. However, it is to be understood that such vehicles are simply exemplary structures and that the present disclosure is capable of broader application in association with the alignment of a wide variety of structures and vehicles. Further examples of such structures and vehicles include gun platforms, military and civilian personnel transport vehicles, and ambulances.

Many larger vehicles, such as RVs, travel trailers, over-the-road truck trailers and the like, have an air suspension system for regulating the height of the vehicle chassis relative to the supporting axles, in a manner that is independent of the load placed in the vehicle, to adjust the height of the chassis in response to the ride conditions experienced by the vehicle. These suspension systems usually consist of a plurality of fluid suspension members, such as air springs, which support the vehicle chassis above the axles. The height of the air springs is controlled by the ingress and egress of pressurized fluid from a suitable source mounted on the vehicle, such as a compressor. One or more intervening valves are traditionally used to facilitate the ingress and egress of pressurized fluid respectively into and out of the air springs, thus adjusting the height of the air springs and correspondingly the position of the vehicle chassis relative to the vehicle axles. Such systems also enable the vehicle chassis to be maintained in an orientation substantially aligned with the axles while the vehicle is stationary. This is accomplished by individually regulating the heights of the air springs that support the vehicle chassis on the axles. One disadvantage of such systems, though, is that the chassis can only be positioned relative to the axles. So, if the axles are disposed in an undesirable orientation, the chassis, though level with the axles, will also be disposed in an undesirable orientation.

As an alternative, many of these vehicles, such as RVs, will also use a plurality of hydraulic jacks, which are lowered in order to level the floor of the RV when in a stationary, parked condition. However, in certain situations, the use of hydraulic jacks is not permitted, such as when the RV is parked on an asphalt parking lot since the jacks could damage the asphalt. Thus, leveling of the vehicle cannot be accomplished under these circumstances. Another disadvantage is the cost associated with these systems, as few of the standard components of the vehicle are utilized therein. That is, the hydraulic jacks, the control valves, the hydraulic lines, the electronic control unit, and the user interface, as well as other components, must be installed on the vehicle, over and above all of the standard components that are already installed. Thus, these extra components increase the cost of the vehicle in order to obtain the leveling feature.

Also, some RVs may use the existing suspension air springs to adjust the floor height and to level the floor by the use of mercury switches, or other controls which will raise and lower certain of the air springs to regulate the height of the floor with respect to the vehicle axles until a level condition is reached. Some examples of such fluid actuated leveling systems for trailers, RVs, etc., are shown in U.S. Pat. Nos. 5,228,704, 5,465,209, 5,180,024, 5,499,845, 6,431,557, and 6,428,026. However, it will be appreciated that these systems may be useful in situations where weight distribution changes in a parked or otherwise stationary vehicle. However, these systems remain ineffective for leveling a vehicle chassis when the axles of the vehicle are not themselves in a level orientation.

The above-listed patents disclose numerous leveling and suspension control systems for air springs in vehicles, some of which are operational while the vehicle is moving, while others are actuated when the vehicle is stationary. Most of these systems use the air springs to regulate the height of the vehicle chassis with respect to the axles or the wheel supporting structure in order to achieve a level condition. Also, many of these systems require separate control systems which are in addition to the existing suspension components and pneumatic ride control system of the vehicle.

For at least these reasons, it is considered desirable to develop an air suspension system that overcomes these as well as other disadvantages.

BRIEF DESCRIPTION

According to one embodiment of this disclosure, described is a method of positioning a vehicle chassis of a vehicle in approximate alignment with a predetermined datum, the vehicle chassis including a first longitudinal end adapted to be pivotally connected to a substantially fixed point and a second longitudinal end, the vehicle including at least one axle associated with the second longitudinal end and a two-corner fluid suspension system including a first corner fluid suspension member disposed between the axle and a first corner associated with the second longitudinal end of the chassis, a second corner fluid suspension member disposed between the axle and a second corner associated with the second longitudinal end of the chassis, a fluid control device, a pressurized fluid source in fluid communication with the fluid suspension members through the fluid control device, an exhaust passage in fluid communication with the fluid suspension members through the fluid control device, an alignment sensor supported on the chassis for outputting a signal indicative of the lateral orientation of the chassis and the longitudinal orientation of the chassis, and an electronic control unit operatively associated with the control of the first corner fluid suspension member and the second corner fluid suspension member, the method comprising a) acquiring the alignment signal generated by the alignment sensor and comparing the alignment signal to the predetermined datum to determine if one or more of the lateral and longitudinal orientation of the chassis is misaligned relative to the predetermined datum and, if the chassis is misaligned, performing the method comprising; b) controlling one or more of the first corner suspension member and the second corner suspension member to laterally align the chassis with a lateral component of the predetermined datum; c) controlling the first corner suspension member and the second corner suspension member to longitudinally align the chassis with a longitudinal component of the predetermined datum, the first corner suspension member and the second corner suspension member controlled to be inflated an equal distance or deflated an equal distance until the chassis is longitudinally aligned with the longitudinal component of the predetermined datum; and d) acquiring the alignment signal generated by the alignment sensor and comparing said alignment signal to the predetermined datum to determine if the lateral orientation of the chassis is aligned with the predetermined datum, and if the chassis is misaligned, repeating steps b), c) and d).

According to another embodiment of this disclosure, described is a suspension system for supporting an associated chassis of an associated vehicle in approximate alignment with a predetermined datum, the vehicle chassis including a first longitudinal end adapted to be pivotally connected to a substantially fixed point and a second longitudinal end, and the associated vehicle including at least one axle supporting the associated chassis substantially near the second longitudinal end, the suspension system comprising a first corner fluid suspension member disposed between the axle and a first corner associated with the second longitudinal end of the chassis; a second corner fluid suspension member disposed between the axle and a second corner associated with the second longitudinal end of the chassis; a fluid control device; a pressurized fluid source in fluid communication with the fluid suspension members through the fluid control device; an exhaust passage in fluid communication with the fluid suspension members through the fluid control device; an alignment sensor supported on the chassis for outputting a signal indicative of the lateral orientation of the chassis and the longitudinal orientation of the chassis; and an electronic control unit operatively associated with the control of the first corner fluid suspension member and the second corner fluid suspension member, the electronic control unit configured to execute instructions to perform a method of positioning the vehicle chassis of the vehicle in approximate alignment with the predetermined datum comprising: a) acquiring the alignment signal generated by the alignment sensor and comparing the alignment signal to the predetermined datum to determine if one or more of the lateral and longitudinal orientation of the chassis is misaligned relative to the predetermined datum and, if the chassis is misaligned, performing the method comprising; b) controlling one or more of the first corner suspension member and the second corner suspension member to laterally align the chassis with a lateral component of the predetermined datum; c) controlling the first corner suspension member and the second corner suspension member to longitudinally align the chassis with a longitudinal component of the predetermined datum, the first corner suspension member and the second corner suspension member controlled to be inflated an equal distance or deflated an equal distance until the chassis is longitudinally aligned with the longitudinal component of the predetermined datum; and d) acquiring the alignment signal generated by the alignment sensor and comparing said alignment signal to the predetermined datum to determine if the lateral orientation of the chassis is aligned with the predetermined datum, and if the chassis is misaligned, repeating steps b), c) and d).

According to still another embodiment of this disclosure, described is a computer program product, that when executed, causes a computer to execute instructions to perform a method of positioning a vehicle chassis of a vehicle in approximate alignment with a predetermined datum, the vehicle chassis including a first longitudinal end adapted to be pivotally connected to a substantially fixed point and a second longitudinal end, the vehicle including at least one axle associated with the second longitudinal end and a two-corner fluid suspension system including a first corner fluid suspension member disposed between the axle and a first corner associated with the second longitudinal end of the chassis, a second corner fluid suspension member disposed between the axle and a second corner associated with the second longitudinal end of the chassis, a fluid control device, a pressurized fluid source in fluid communication with the fluid suspension members through the fluid control device, an exhaust passage in fluid communication with the fluid suspension members through the fluid control device, an alignment sensor supported on the chassis for outputting a signal indicative of the lateral orientation of the chassis and the longitudinal orientation of the chassis, and an electronic control unit operatively associated with the control of the first corner fluid suspension member and the second corner fluid suspension member, the method comprising: a) acquiring the alignment signal generated by the alignment sensor and comparing the alignment signal to the predetermined datum to determine if one or more of the lateral and longitudinal orientation of the chassis is misaligned relative to the predetermined datum and, if the chassis is misaligned, performing the method comprising; b) controlling one or more of the first corner suspension member and the second corner suspension member to laterally align the chassis with a lateral component of the predetermined datum; c) controlling the first corner suspension member and the second corner suspension member to longitudinally align the chassis with a longitudinal component of the predetermined datum, the first corner suspension member and the second corner suspension member controlled to be inflated an equal distance or deflated an equal distance until the chassis is longitudinally aligned with the longitudinal component of the predetermined datum; and d) acquiring the alignment signal generated by the alignment sensor and comparing said alignment signal to the predetermined datum to determine if the lateral orientation of the chassis is aligned with the predetermined datum, and if the chassis is misaligned, repeating steps b), c) and d).

The present disclosure provides an electronic control system for leveling a vehicle chassis, such as the frame, subframe, floor and/or body of an RV or over-the-road trailer, for example, which uses the existing air suspension components for the vehicle ride system, avoiding additional and costly duplicate components and additional space usage in order to provide the desired leveling effect for the vehicle chassis, especially when the vehicle is stationary.

Another feature of the disclosure is to provide a leveling system that requires only the addition of an alignment sensor or other level detection device, such as an accelerometer, tilt sensor, gyro, or similar type sensor, for example. The alignment sensor is supported on the vehicle chassis and operationally connected with an electronic control unit (ECU), which is used to control the ride suspension system in combination with software for the ECU for performing a method of the present disclosure.

Still another feature of the disclosure is to provide a horizon leveling control system that aligns the vehicle chassis with respect to an artificial horizon or other predetermined datum independent of the distance of the vehicle chassis from the axles or wheels, by introducing this artificial horizon or predetermined datum into the software of the ECU.

Another feature of the disclosure is to provide the system with an interlock via the standard height leveling system to ensure that the ECU automatically disengages the horizon leveling system of the disclosure and goes to the normal ride height leveling upon movement of the vehicle or placement of the vehicle in a transmission gear in preparation for subsequent movement.

A further aspect of the disclosure is to enable the system to determine whether the individual air springs have sufficient travel to enable the vehicle to achieve a level condition after the tilt or orientation of the vehicle is initially determined by the system before attempting to perform the actual leveling by introducing or exhausting air into or from selected air springs.

A further feature of the disclosure is the ability to regulate the heights of the individual air springs in a particular sequence, such as initially adjusting for large magnitudes of unevenness by adjusting the air springs on one side of the vehicle, after which smaller magnitudes of height can be compensated for by individually adjusting either the front or rear air spring on the selected one side of the vehicle.

Still another advantage of the present disclosure is to enable the system to initially exhaust air from the air springs on a high side or corner of the vehicle after the unevenness is detected by the level detection device, prior to introducing additional pressurized fluid into one or more of the air springs to raise a lower side, thereby reducing the depletion of the supply of pressurized fluid and minimizing additional work by the vehicle compressor.

Another feature of the disclosure is to provide a horizon leveling system and method of aligning a two-corner air suspension system with an artificial horizon. The two-corner air suspension system may be associated with a single axle trailer which is normally pulled behind a tow-vehicle. Also, the two-corner air suspension system may be associated with a two axle vehicle that includes an air suspension system on only two corners thereof, for example, the rear of the vehicle. One example of the former is a travel trailer or camper that has an air suspension system and is towed behind a vehicle through the use of a ball-hitch or fifth-wheel connection. One example of the latter is a pick-up truck that has a front suspension with steel springs (e.g. coil or leaf springs) and a rear suspension with air springs.

In summary, the disclosure provides a horizon leveling system that utilizes most of the features and components of the air suspension ride system of a vehicle, such as an RV, travel trailer or over-the-road trailer, for example, by the addition of a level detection device and by programming the ECU with an artificial horizon or other predetermined datum. The present system is adapted to adjust the orientation of the vehicle chassis into alignment with the artificial horizon irregardless of the position of the vehicle axles.

The foregoing advantages, construction and operation of the present disclosure will become more readily apparent from the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a four-corner horizon leveling system and components thereof mounted on a traditional dual axle vehicle.

FIG. 2, which includes subfigures 2A, 2B, and 2C, is a flow diagram of one method of the present disclosure for carrying out the alignment of a four-corner vehicle chassis.

FIG. 3, which includes subfigures 3A, 3B, and 3C, is a flow diagram of a modified method for alignment of the four-corner vehicle chassis.

FIG. 4 is a diagrammatic representation of the manner in which the vehicle chassis is aligned by the methods shown by the flow diagrams of FIGS. 2 and 3.

FIG. 5 is a diagrammatic side view of a vehicle to be aligned by the four-corner horizon leveling method and system of the present disclosure.

FIG. 6 is an enlarged fragmentary sectional view taken on line 6-6 in FIG. 5.

FIG. 7 is a diagrammatic view looking in the direction of line 7-7 in FIG. 5.

FIG. 8 illustrates a control panel for use with a four-corner horizon leveling system.

FIG. 9 is a flow diagram of one exemplary method of determining if an adjustment is within the capability of a suspension system.

FIG. 10 is a flow diagram of one exemplary method of calibrating a sensor to a predetermined datum.

FIG. 11 is a schematic diagram of a two-corner horizon leveling system and components thereof mounted on a traditional single axis trailer.

FIG. 12 is a flow diagram of a method for alignment of a vehicle including a two-corner horizon leveling system as illustrated in FIG. 11.

FIG. 13, which includes subfigures 13A, 13B and 13C, is a flow diagram of one method of the present disclosure for carrying out the alignment of a vehicle chassis utilizing a two-corner air suspension system.

FIG. 14 is a flow diagram of another method for alignment of a trailer including a two-corner horizon leveling system as illustrated in FIG. 12, wherein the system cooperates with a towing vehicle which raises or lowers a ball hitch to provide further longitudinal alignment of the trailer.

FIG. 15, which includes subfigures 15A, 15B and 15C, is a flow diagram of a method for carrying out the alignment of a vehicle chassis utilizing a chassis associated two-corner air suspension system and the suspension system associated with a towing vehicle.

FIG. 16 is a diagrammatic side view of a towing vehicle and a trailer to be aligned by the two-corner horizon leveling method and system of the present disclosure.

FIG. 17 is an enlarged fragmentary sectional view taken on line 17-17 in FIG. 16.

FIG. 18 is a diagrammatic view looking in the direction of line 18-18 in FIG. 16.

FIG. 19 is a diagrammatic side view of a pick-up truck including a rear two-corner horizon leveling method and system of the present disclosure.

FIG. 20 is a diagrammatic view looking in the direction of line 20-20 in FIG. 19.

FIG. 21 illustrates a control panel for use with a two-corner horizon leveling system.

Similar numerals refer to similar parts throughout the drawings.

DETAILED DESCRIPTION

It is to be understood that the term chassis, as recited herein, generally refers to the sprung mass of the vehicle, which typically includes one or more of the components supported on the fluid suspension members. This can include, but is not limited to, a frame, a subframe, a floor and/or a body of the vehicle, for example. Additionally, the terms level, leveling and the like as used herein, such as in the term “horizon leveling,” for example, are not intended to be in any way limited to horizontal or vertical leveling. Rather, such terms refer to substantial alignment with a predetermined datum regardless of the orientation of the predetermined datum.

Further, the term “vehicle”, as recited herein, includes, but is not limited to a two-axle motorized truck, RV, automobile, etc. and a single and multiple axle trailerable non-motorized camper, trailer, etc.

FIG. 1 is a diagrammatic representation of the horizon leveling system of the present disclosure which is indicated generally at 1, and illustrated as being used on a vehicle 2, such as an RV, for example. However, system 1 can be used on other types of vehicles such as travel trailers, over-the-road truck trailers, ambulances, and personnel transport vehicles, for example. The system can also be used on stationary equipment, such as a gun platform, for example, that is supported on fluid suspension members, such as air springs, for example. Vehicle 2 includes a plurality of wheels 3, one of which is illustrated on each corner of the vehicle, and a fluid suspension system FSS. The fluid suspension system includes air springs 6, 7, 8 and 9 mounted adjacent each wheel 3 on the ends of supporting front and rear axles 11 and 12 and supports a vehicle chassis 4 thereon. For smaller vehicles, only a single axle having a single pair of air springs may be utilized. However, for most RVs or other large pieces of equipment or vehicles, at least a pair of axles will be utilized having one or more air springs adjacent each end thereof.

The air springs are of a usual construction having a pair of spaced end members 15 and 16 (FIG. 6) with an intervening flexible sleeve 17 forming an internal fluid chamber. Some examples of known air springs are shown in U.S. Pat. Nos. 5,374,037, 4,852,861, and 4,718,650, which are incorporated herein by reference. Air-over-damper type suspension members also can be used within the scope of the present disclosure, such as is shown in U.S. Pat. No. 4,712,776 and which is incorporated herein by reference.

Leveling system 1 includes a compressor 20, which can be electrically operated or driven by the engine of the vehicle or in another suitable manner, to supply pressurized fluid, usually air, through a supply line 21 to a reservoir or supply tank 22. It will be appreciated that such compressors are known to be operable independent of the engine of the vehicle. A dryer 23 can optionally be included and is preferably fluidically interconnected along line 21 for removing moisture from the pressurized fluid prior to entering reservoir 22. If desired, pressurized fluid can be supplied directly to the air springs from the compressor without first going to reservoir 22.

A main control valve assembly 25 includes an inlet valve 26, an exhaust valve 27 and individual air spring control valves 28, 29, 30 and 31. Inlet valve 26 is in fluid communication with reservoir 22 through fluid supply line 33 and exhaust valve 27 is in fluid communication with an exhaust silencer 34. Individual control valves 28, 29, 30 and 31 are connected in fluid communication with individual air springs 6, 7, 8 and 9, respectively, by fluid lines 35, 36, 37 and 38, respectively. It is to be distinctly understood that valve assembly 25 described above and illustrated in FIG. 1 is merely one example of a suitable valve assembly and that any other suitable arrangement can be used without departing from the principles of the present disclosure. For example, multi-position valves, such as 2-way or 3-way valves for example, could be used in place of one or more of the control valves shown and described.

Each of the air springs can optionally have a height sensor or detector, indicated generally at 40, associated therewith that can be any one of various known constructions. Height sensors 40 could utilize the Hall effect, sonics, infrared, resistance, or the like, that operate on, in or merely in association with the air springs and of which all are well known in the air spring art. Some examples of such air spring height detectors that are part of an air spring itself are shown in U.S. Pat. Nos. 5,707,045, 5,229,829, and 4,798,369, which are incorporated herein by reference. However, as shown in FIG. 6, height sensor 40 can be a separate component externally supported on the vehicle and extending between spaced-apart portions of the vehicle, such as between the axle and chassis or vehicle body, for example. Each height sensor 40 is preferably supported adjacent one of the individual air springs and is also in communication with an electronic control unit (ECU) 42, such as by a control line 43. Additionally, an end-of-travel signal can be output by the height sensors indicating that one of the extreme positions, such as fully extended or fully compressed, for example, of the associated air spring has been reached or is being approached. Alternately, end-of-travel data can be determined by the ECU based upon a comparison of the signal from the height detector with known end-of-travel values stored within the ECU. ECU 42 is shown in FIG. 1 as being connected to an optional service switch 45 by control line 46 for selectively actuating the hydraulic jacks that are optionally provided on many RVs. Optionally, the switch can also include ON and/or OFF positions (FIG. 8) for the automatic leveling system used during operation of the vehicle. ECU 42 also is connected to a height switch 49 by a control line 50, to the key actuated vehicle ignition switch 51 by a control line 52, and to a pair of indicating lights 55 and 56 by control lines 57 and 58, respectively. Height switch 49 can optionally be a multi-position height selection switch for use when the vehicle is selectively operable at a plurality of heights. ECU 42 also is operatively connected to the vehicle speed indicator or speedometer 59 by a control line 60, and to the individual air spring control valves in valve control unit 25 by a plurality of control lines, indicated collectively at 61. As such, ECU 42 is adapted to selectively actuate one or more of the plurality of valves. It will be appreciated that any suitable speed or movement indicating device can be operatively connected to the ECU in addition to or as an alternative to speedometer 59.

Many of the above-described components and manner of use are standard on many vehicle air suspension systems used for RVs and trailers to provide a multi-position leveling system and desired ride characteristic for the vehicle. Additionally, it will be appreciated that communications to and from the various devices and components of the vehicle, such as ECU 42, height switch 49 and speedometer 59, for example, can be transmitted in any suitable manner. For example, each of the devices and components can be hard-wired to one another as prescribed by each of the various systems operative on the vehicle, with the signals communicated between the devices and components along the individual wires. As an example, if five different systems of the vehicle rely upon a signal from the speedometer, five different wires may be interconnected to the speedometer to provide the signal output by the speedometer to each of the systems directly. However, many vehicles now include a CAN bus communication system that networks the various devices and components together. Such CAN bus communications systems are well known and commonly used. These systems can include a standalone controller or alternately be integrated into another controller of the vehicle, such as ECU 42, for example. One example of a suitable standard or protocol for such systems is SAE J1939. Though, it will be appreciated that a variety of other protocols exist and could alternately be used, such as CANOpen and DeviceNET, for example. One advantage of using a CAN bus communication system is that the actual physical wiring of the vehicle is greatly simplified. Another advantage is that the addition of a new device and/or system can be accomplished without significant physical modification of the vehicle. For example, the new system can be added to the vehicle simply by suitably mounting a new device on the vehicle, placing the device into communication with the CAN bus communication system, and making any attendant software and/or firmware modifications to the existing devices and/or components. Once installed, the new system can send and receive any other signals, information and/or data through the CAN bus communication system to operate the newly added system.

In accordance with the disclosure, an alignment sensor or level detection device, which is indicated generally at 65 and shown diagrammatically in FIGS. 5-7, is mounted on or operatively connected to vehicle chassis 4. Device 65 provides an alignment signal to ECU 42 through a control line 66. The alignment signal is indicative of the orientation of the vehicle chassis. Level detection device 65 can be of any suitable type of apparatus, such as an accelerometer, tilt sensor, gyroscopic sensor, and a transducer or other device that can detect the position, orientation or amount of tilt of a structural body and provide a signal, such as a relative voltage or current, as to the approximate position, orientation or amount of tilt of the structural body associated therewith. One particular type of level detection device is a dual-axis accelerometer manufactured by Memsic, Inc. of North Andover, Mass., identified as model MXR299ML. This sensor operates on a thermal principle, generating a signal, such as an output voltage, for example, for both the X-axis and Y-axis that varies according to the angular orientation of the sensor. Accelerometer 65 provides an analog or digital value or signal that is dependent upon the tilt or out of level of the vehicle chassis upon which the sensor is supported. This signal is supplied to ECU 42 through line 66. Accelerometer 65 can be attached to any part of the vehicle chassis without affecting the disclosure. For example, the accelerometer could be secured to a portion of a frame, such as a cross beam, or to a portion of the body, such as a roof, side wall or floor. Additionally, the accelerometer can optionally be mounted centrally on the vehicle chassis. However, central mounting is not required.

Thus, in accordance with one of the features of the disclosure, a typical air suspension system for a vehicle as described above, is utilized without material modifications thereto with the exception of incorporating an alignment sensor or level detection device 65 that is operationally connected to ECU 42, in combination with the appropriate software utilized by ECU 42, to provide the features set forth in FIGS. 2-4, and discussed below.

FIG. 8 represents a type of control panel 70 which can be located on the dashboard of the vehicle for controlling both the ride suspension system for the vehicle during the dynamic operation thereof as well as the horizon leveling system of the present disclosure. Panel 70 includes height switch 49 that controls the usual ride leveling system for the vehicle, indicating lights 55 and 56, the service switch 45, and a horizon leveling switch 72 that is connected to ECU 42 by a control line 73 (FIG. 1). An indication light 74 is connected to ECU 42 by a control line 69. Service switch 45 will be moved to one of three positions as shown in FIG. 8. The switch position can be illuminated by back lighting to indicate the selected position. If desired, panel could be a touch screen which would eliminate the toggle or rocker switches discussed above.

In accordance with one of the features of the disclosure, an artificial level position or horizon is indicated schematically by dot-dash line 71 (FIGS. 5 and 6). This artificial horizon is programmed into ECU 42 as the predetermined datum. The predetermined datum is an imaginary reference plane that the system uses to align the vehicle chassis irrespective of the orientation of the axles, wheels of the vehicle or the supporting ground. Though line 71 is shown in FIGS. 5 and 6 as being substantially horizontal, it will be appreciated that line 71 could be disposed in any desired orientation as established hereinbefore.

The steps for carrying out one embodiment of the present disclosure are illustrated in FIG. 2, with a second embodiment being illustrated in FIG. 3, by the flow charts contained therein. Referring to FIG. 2, the vehicle operator, after the vehicle comes to a stop in an area such as a parking lot, campground, or the like, will actuate the horizon leveling system by actuating control switch 72 located on panel 70 in the cab portion of the vehicle, as indicated by block 75 (FIG. 2A). In one preferred arrangement, this is done by depressing and holding control switch 72 for a predetermined period of time. A similar button hold can also be used to disengage the system. Thus, the opportunity for inadvertently initiating (or alternately, disengaging) the system, such as by bumping the switch, for example, is minimized. One example of a suitable duration for holding the switch in the depressed position is from about 3 to about 10 seconds and preferably about 4 seconds.

ECU 42 initially determines whether the vehicle chassis is aligned with the predetermined datum at block 77 by comparing the signals received from accelerometer 65 with respect to the artificial horizon 71 preset in ECU 42. If the vehicle floor or other reference plane is within an acceptable range on either side of artificial horizon 71 the ECU will send a signal and actuate indicator light 74, as represented by block 78, which will visually advise the driver that the vehicle is properly aligned. If the ECU senses that the vehicle chassis is out of alignment with the predetermined datum, it will then determine if the magnitude that the vehicle chassis is out of alignment is within the capability of the system to correct at block 79. If outside the capability of the system, it will send a signal to the operator, such as an audible tone or a flashing light 74, as shown by block 80, which immediately advises the driver that the vehicle is excessively uneven and that the suspension system will not be able to sufficiently compensate for the uneven terrain on which the vehicle is currently parked. The driver can then reposition the vehicle at that location or go to a different, more level location. If the out-of-level signal generated by accelerometer 65 is within the capability of the system to correct, the ECU will then proceed to block 81 where it will detect which side of the vehicle is above artificial horizon 71, that is, right side 62 or left side 63, as shown in FIG. 7.

One example of performing block 79 is shown in FIG. 9 and includes a block 79A of providing end-of-travel data, such as from a height sensor, for example, indicative of one of the extreme positions of an air spring. Block 79 can also include a block 79B of storing the end-of-travel data in an ECU, for example. Block 79 can further include a block 79C of acquiring a signal indicative of the orientation of the vehicle chassis, such as from a height detector or an alignment sensor, for example. Block 79 can include still a further block 79D of comparing the signal indicative of orientation to the stored end-of-travel data. Still a further block 79E of determining if any difference between the signal and the end-of-travel data exceeds a predetermined value can be included in performing block 79. Another block 79F of selectively operating the control device to discontinue pressurized fluid flow if the predetermined value is exceeded can also be included in block 79.

Upon determining at block 81 which is the high side of the vehicle, a determination then is made at block 82 (assuming for the purpose of this description that the right side was determined to be the high side) as to whether the amount of unevenness is within the capability of the suspension system to correct. If a determination is made that the right side can be lowered sufficiently at block 82, a signal is then sent via block 83 to block 84 (FIG. 2C) to determine if the front 62A or the rear 62B of right side 62 is out of alignment. After the determination is made at block 84 that the front or rear is out of alignment, block 85 determines whether it can be lowered sufficiently to correct for the detected unevenness, and if permissible, block 86 provides the signal to lower the appropriate air spring by exhausting air therefrom, such as from air spring 6 since this is the air spring on the rear right side of the vehicle chassis.

If the right side 62 cannot be lowered sufficiently, block 88 (FIG. 2B) determines if the opposite side 63 can be raised sufficiently to compensate for the unevenness. If not, block 89 flashes indicating light 74 alerting the driver that the system is still checking if the proper alignment can be achieved. If left side 63 can be raised sufficiently, block 90 through block 84 then determines, as discussed above, if the front or rear of the left side is out of alignment, and whether it can be lowered to reach the desired aligned position.

Again, if the previously determined front or rear cannot be lowered, determination is made by block 88 if the opposite front or rear can be raised. If not, block 91 flashes light 74 that the desired alignment has yet to be achieved. After alignment has been achieved and recognized at block 77 and the appropriate signal sent to light 74 via block 78 (FIG. 2A), a timer circuit represented by block 92, rechecks the alignment of the vehicle chassis after a preset time period, such as one, two, etc., hours by the previous described sequence, and will make the needed correction, preferably by exhausting air from the high side air springs, in order to maintain the system alignment.

It is understood that if left side 63 of the vehicle is determined by block 81 to be the high side, the same procedure is performed as discussed above for the right side.

Also, if the front end is determined to be out of level at block 84, the same procedure is performed for the front end as discussed above for the rear end. It is preferred that the air spring or springs on the high side or end be lowered before the air spring or springs on the lower side or end be raised since this involves only exhausting air from the individual air spring which will not deplete the supply of pressure air in reservoir 22. However, if necessary, the appropriate air spring can be raised by supplying it with additional pressurized fluid from reservoir 22. This feature avoids prematurely using the supply of pressurized fluid from reservoir 22.

Thus, the ECU initially determines, depending upon the reading received from level indicating device 65, whether the amount of unevenness is too great to be compensated for by the system and to initially alert the operator to relocate the vehicle. This avoids the need to attempt the alignment of the vehicle body by actuation of the appropriate air springs only then to find out that the vehicle body cannot be aligned due to the excessive unevenness of the terrain. This saves time and unnecessary manipulation of the air spring components, fluid supplies, etc. Also, the system determines which side of the vehicle is the high side and then whether it can be compensated and, again, whether this unevenness can be compensated for and then which corner or end of the high side can be lowered to bring the vehicle body into alignment with the artificial horizon or predetermined datum stored in ECU 42.

Again, air is preferably exhausted from the high side air springs or just a corner air spring rather than introduce air into the lower air springs to achieve the desired level to conserve the stored pressurized fluid. Also, it is preferred to lower the vehicle chassis, sides, or corners to achieve the desired levelness as opposed to raising one side or corner thereof to achieve the desired levelness, since a lower vehicle chassis, when stationary, facilitates the ingress and egress of the occupants into and out of the vehicle chassis. Thus, if the vehicle chassis was initially raised to achieve the levelness, it would make the ingress and egress slightly more difficult. Again, it is not the height of the vehicle chassis above the wheels or axles that is controlling, it is the adjusting of the alignment of the vehicle body to a preset artificial horizon that is utilized by the improved system of the present disclosure.

ECU 42 preferably includes a standard microchip that can be programmed by one skilled in the art to provide those features discussed above and shown in FIGS. 2-4.

A modified embodiment of the improved method is shown in FIGS. 3A-3C. After a determination is made at block 79 that the magnitude of unlevelness is within the capability of the system, a determination is then made at block 100 as to what is the direction that is out of alignment, namely, as shown in FIG. 3B, whether it is the right front, left front, left rear, right rear, or entire front, the entire rear, the entire left side, or the entire right side of the vehicle chassis. After this determination is made by one of the blocks as shown in FIG. 3B, the system proceeds to the blocks of FIG. 3C which then determines at block 101 whether the location that is out of alignment can be sufficiently lowered and, if so, whether it would be the lower side as determined by block 102 or lower corner as determined by block 103. Again, if the out of alignment location cannot be effectively lowered, the system then determines, as shown by the alternate blocks in FIG. 3C, whether the opposite location, whether it be a side, end, or corner, can be raised to compensate for the misalignment. Again, light 74 will be flashed as shown by blocks 105 if aligning the misaligned area cannot be achieved, in a similar manner as discussed above for the embodiment of FIG. 2. After it has been determined that the desired alignment can be achieved by lowering a particular location on the vehicle chassis, the appropriate air spring is actuated through the appropriate control valve 28-31 for exhausting air from one or more of the air springs or, if necessary, to supply air to the appropriate air spring via the associated control valve to raise the unlevel corner, side, or end of the vehicle chassis.

The difference between the method of FIGS. 2 and 3 is that the method shown by the flow diagrams in FIG. 2 initially determine which side is out of alignment, after which it is determined whether it is the front or rear of that side that needs to be adjusted, whereas the method depicted by the flow diagram of FIG. 3 determines immediately which location of the vehicle chassis is out of alignment for subsequent correction.

FIG. 4 is another diagrammatic representation of how the system functions to achieve the alignment with respect to the analog or digital signal supplied by accelerometer 65. Center point 110 represents the exact alignment in both the X and Y axis determined by accelerometer 65. In this situation, the accelerometer will output signals corresponding to a midrange value or a value around the accelerometer's calibrated midpoint 110 from both the X and Y axis readings which indicates that both planes are level with the predetermined datum. The inner dot-dash circle 111 represents that position which, when reached, will indicate that the vehicle chassis or, alternatively, the floor or other part of the vehicle chassis being monitored, is substantially aligned with the predetermined datum. Outer concentric circle 112 represents the maximum unlevelness that can be compensated for by the vehicle and its suspension system.

In the particular example of FIG. 4, upon the output signal exceeding the value represented by circle 112, it will indicate that the misalignment or tilt is excessive and cannot be compensated for by the vehicle suspension system, such as represented by block 79 of FIG. 2A or other blocks 89, FIGS. 2B and 2C. As an example, assume that the two signals provided by accelerometer 65 intersect at point 113, which indicates that the front part and left side must be lowered until this point reaches inner circle 111. If the measured point falls within inner circle 111, no further alignment is required by the system. It will be appreciated that such a determination of excessive misalignment can be used in addition to or as an alternative to the end-of-travel analysis described above. However, should this point value fall outside of outer circle 112, such as shown by point 115, the system then indicates that too great a degree of misalignment exists and the capability of the suspension system to correct the misalignment is exceeded.

Under certain circumstances, it may be determined that the orientation of the chassis is or was within the capability of the suspension system to level but after one or more leveling operations a level condition cannot be achieved. These situations are represented by blocks 89 and 91 in FIGS. 2B and 2C, as well as blocks 104 and 105 in FIG. 3C. An example of such a situation might be where the operator has inadvertently parked the vehicle adjacent a foreign object that impedes the lowering of a portion of the chassis. In such a situation, the suspension system could have the capacity to fully level the vehicle, but the foreign object will only permit the chassis to be partially leveled. In FIG. 4, for example, the initial orientation of the chassis is indicated by the point 113 and the partially leveled condition is indicated by point 113′. Under such a circumstance, an indication, such as a flashing light or an audible signal, for example, can be output, such as from control panel 70, for example, to the operator of the vehicle to indicate that the vehicle has been partially leveled but remains outside of the fully leveled condition. Thus, the operator is given the option to reposition the vehicle for full leveling or accept the existing partially leveled condition.

It is to be distinctly understood that the artificial horizon or predetermined datum referred to herein is not in any way limited to a horizontal or substantially horizontal plane. Rather the predetermined datum can be a plane aligned in any desired orientation relative to the X-axis, Y-axis or any combination thereof without departing from the principles of the present disclosure. One method 200 of calibrating the predetermined datum is illustrated in FIG. 10, and includes physically positioning the vehicle chassis in the desired orientation, such as where the floor of the chassis is substantially horizontal or tilting from back to front with the front being substantially lower than the back, for example, as indicated in block 202. Once the vehicle chassis is physically oriented, a signal indicating the orientation is acquired from the alignment sensor, as indicated in block 204, and the data associated with the signal is stored in the ECU as alignment data, as indicated in block 206. Thereafter, the system operates as discussed above and repeatedly compares the signal's output from the alignment sensor to the alignment data in the ECU.

Thus, the improved system and method of the present disclosure enables a vehicle chassis and, in particular, the floor or other wall of an RV, trailer or other structure, to be aligned easily and efficiently by utilizing the existing air suspension ride system of the vehicle, by the addition of accelerometer 65 or other type of alignment sensor in combination with ECU 42, which has been programmed according to the flow diagrams shown in FIGS. 2 and 3. ECU 42 interprets the return values from the X and Y plane readings provided by accelerometer 65 and makes height adjustments to the vehicle via the height control componentry and, in particular, the ride suspension air springs, in order to get the vehicle chassis aligned with the predetermined datum, irrespective of the orientation of the ground, wheels or axles of the vehicle. The system preferably uses the existing ECU unit which is used for the normal ride suspension system and leveling with various modifications thereto in order to achieve the flow diagram and the results shown in FIGS. 2 and 3.

The control system of the present disclosure also is provided with suitable interlocks that act to selectively deactivate at least a portion of the horizon leveling system and returns the system to the normal ride height leveling upon actuation of switches 45 and/or 49. Immediately upon any of these switches being actuated, the ECU preferably automatically disengages the automatic leveling system of the present disclosure. Also, speedometer 59 and/or another suitable movement-sensing component is preferably connected with ECU 42, such as through line 60, for example, to further signal ECU 42 to selectively deactivate the horizon leveling system upon the vehicle being put into motion. Thus, where the speedometer or other device output a signal indicative of a speed greater than about zero (0) mph, one of the alignment sensor and at least a portion of the ECU can be deactivated. Also, leaving “Park” or releasing the emergency brake could optionally signal ECU 42 to disengage the leveling system. As discussed above, the system initially attempts to adjust the height of the vehicle by exhausting air from the high side or end air springs to conserve the stored pressurized fluid in the reservoir 22. However, if necessary, air can be supplied to the appropriate air springs from reservoir 22 through the appropriate individual control valves 28-31 to raise that portion of the vehicle body to compensate for any misalignment if necessary and/or if desired.

It is readily understood that air suspension ride systems, other than that shown in FIG. 1, could be utilized without affecting the concept of the disclosure, since one of the main features is the setting of the artificial horizon level and the adjusting of the appropriate air spring/springs to achieve this position, which is determined through an alignment sensor or level detection device, such as accelerometer 65, for example. Again, other types of level detecting devices could be utilized without affecting the concept of the disclosure. Likewise, the present system can be used on stationary equipment other than vehicles, and the air springs replaced with hydraulic pressure members, etc., without affecting the disclosure.

With reference to FIGS. 11-21, now will be described a two-corner air suspension system and method which aligns a vehicle or trailer chassis with an artificial horizon. The disclosed system and methods are especially useful on a single axle trailer which is pulled behind a tow-vehicle as well as on vehicles that have an air suspension system on only two corners thereof. One example of the former is a travel trailer or camper that has an air suspension system and is towed behind a vehicle through the use of a ball-hitch or fifth-wheel connection. One example of the latter is a pick-up truck that has a front suspension with steel springs (e.g. coil or leaf springs) and a rear suspension with air springs.

Both of the above arrangements represent constructions that utilize two-corner air suspension systems. Such constructions are adjustable in the lateral (i.e., side-to-side) direction and in the longitudinal (i.e., front-to-back) direction. For a trailer, the hitch or connection acts as a flexible pivot point about which both lateral and longitudinal adjustments can be made to align the trailer with an artificial horizon. For a vehicle, the front axle and front suspension springs act as a semi-flexible pivot point such that the sprung mass can pivot longitudinally about the front axle and can pivot laterally against the front suspension springs.

With the exception of the controller, a two-corner air suspension system in accordance with the subject matter of the present disclosure can utilize otherwise conventional air springs and suspension system components, such as those previously described. For example, such an air suspension system could include an ECU, a cab mounted display, a trailer mounted display, one or more height sensors for determining the height of the chassis, a dual axis accelerometer to measure the lateral and longitudinal orientation of the vehicle chassis or trailer and, optionally, one or more pressure sensors to measure the air pressure associated with the air suspension system, i.e. air spring pressure.

As shown in FIG. 12, a method of aligning a two-corner air suspension system can include an iterative process in which a lateral axis is adjusted to predetermined datum associated with a lateral artificial horizon and then a longitudinal axis is adjusted to predetermined datum associated with a longitudinal artificial horizon. After the lateral and longitudinal alignment of the vehicle or trailer is within a predetermined tolerance, the iterative process ends. Such a method of operation can be performed by an ECU or other controller executing algorithms to determine the appropriate air spring to raise or lower for lateral and/or longitudinal alignment as a function of the orientation of the vehicle or trailer.

Conventional four-corner suspension systems, as previously described, can utilize end-of-travel signals and/or data (e.g., from height sensors) to determine whether the vehicle chassis can be adjusted into approximate alignment with the artificial horizon. A two-corner suspension system in accordance with the present disclosure can also utilize such end-of-travel signals and/or data to ensure that the suspension system is capable of undergoing the desired displacement. Furthermore, a two-corner suspension system in accordance with the present disclosure can also include a suitable method for determining whether the pivot point is capable of permitting the desired adjustment. As one example, an ECU can execute algorithms to determine if the suspension system has reached its adjustability limit of the pivot point. This can be done in any suitable manner, such as by utilizing signals and/or data from the height sensors or by monitoring loads on the two different sides of the vehicle (e.g., by monitoring air pressure within the air springs).

According to another aspect of the present disclosure, additional longitudinal alignment of a trailer is provided by operatively connecting the rear suspension system associated with a towing vehicle to an operatively connected trailer. In operation, the towing vehicle suspension system can raise or lower the rear pivot point, i.e. hitch, associated with the towing vehicle to longitudinally align the trailer with a predetermined datum associated with an artificial horizon.

With the exception of the controller, a two-corner air suspension system in accordance with this aspect of the present disclosure can utilize otherwise conventional air springs and suspension system components, such as those previously described with reference to FIGS. 1-10. For example, such an air suspension system could include an ECU, a cab mounted display, a trailer mounted display, one or more height sensors for determining the height of the chassis, a dual axis accelerometer to measure the lateral and longitudinal orientation of the vehicle chassis or trailer and, optionally, one or more pressure sensors to measure the air pressure associated with the air suspension system, i.e. air spring pressure.

As shown in FIG. 13, a method of aligning a two-corner air suspension system utilizing the suspension system of the towing vehicle can include an iterative process in which a lateral axis is adjusted to predetermined datum associated with a lateral artificial horizon and then a longitudinal axis is adjusted to predetermined datum associated with a longitudinal artificial horizon, the longitudinal axis adjusted by inflating or deflating both of the trailer rear two-corner air springs equally and/or controlling the towing vehicle suspension system to raise or lower the front of the trailer. After the lateral and longitudinal alignment of the trailer is within a predetermined tolerance, the iterative process ends. Such a method of operation can be performed by an ECU or other controller executing algorithms to determine the appropriate air spring to raise or lower for lateral and/or longitudinal alignment as a function of the orientation of the vehicle or trailer.

FIG. 11 is a diagrammatic representation of a two-corner horizon leaving system which is indicated generally at 301 and illustrated as being used on a towed vehicle, i.e. trailer, such as a single axle trailerable camper. However, system 301 can be used on other types of vehicles, such as cargo trailers, pick-up trucks, etc. The system can also be used on stationary equipment, such as a gun platform, for example, that is supported on a two-corner fluid suspension system including air springs, for example. The exemplary trailerable vehicle includes a pair of wheels 303, one of which is illustrated on the left rear corner and right rear corner of the vehicle, and a fluid suspension system FSS. The fluid suspension system includes air springs 307 and 309 mounted adjacent each wheel 303 on the ends of the rear axle 312 and supports the trailer chassis 304 thereon. Alternatively, for larger trailerable vehicles, a tandem rear axle arrangement may be utilized, where each axle is associated with a pair of air springs.

As previously described with reference to FIG. 1, the air springs are of a usual construction having a pair of spaced end members 315 and 316 (FIGS. 16 and 17) with an intervening flexible sleeve 317 forming an internal fluid chamber. Some examples of known air springs are shown in U.S. Pat. Nos. 5,374,037, 4,852,861, and 4,718,650, which are incorporated herein by reference. Air-over-damper type suspension members also can be used within the scope of the present disclosure, such as is shown in U.S. Pat. No. 4,712,776 and which is incorporated herein by reference.

Leveling system 301 includes a compressor 320, which can be electrically operated or driven by the engine of the towing vehicle or in another suitable manner, to supply pressurized fluid, usually air, through a supply line 321 to a reservoir or supply tank 322. It will be appreciated that such compressors are known to be operable independent of the vehicle. A dryer 323 can optionally be included and is preferably fluidically interconnected along line 321 for removing moisture from the pressurized fluid prior to entering reservoir 322. If desired, pressurized fluid can be supplied directly to the air springs from the compressor without first going to reservoir 322.

A main control valve assembly 325 includes an inlet valve 326, an exhaust valve 327 and individual air spring control valves 329 and 331. Inlet valve 326 is in fluid communication with reservoir 322 through fluid supply line 333 and exhaust valve 327 is in fluid communication with an exhaust silencer 334. Individual control valves 329 and 331 are connected in fluid communication with individual air springs 307 and 309, respectively, by fluid lines 336 and 338, respectively. It is to be distinctly understood that valve assembly 325 described above and illustrated in FIG. 11 is merely one example of a suitable valve assembly and that any other suitable arrangement can be used without departing from the principles of the present disclosure. For example, multi-position valves, such as 2-way or 3-way valves for example, could be used in place of one or more of the control valves shown and described.

Each of the air springs can optionally have a height sensor or detector, indicated generally at 340, associated therewith that can be any one of various known constructions. Height sensors 340 could utilize the Hall effect, sonics, infrared, resistance, or the like, that operate on, in or merely in association with the air springs and of which all are well known in the air spring art. Some examples of such air spring height detectors that are part of an air spring itself are shown in U.S. Pat. Nos. 5,707,045, 5,229,829, and 4,798,369, which are incorporated herein by reference. However, as shown in FIG. 17, height sensor 340 can be a separate component externally supported on the vehicle and extending between spaced-apart portions of the vehicle, such as between the axle and chassis or vehicle body, for example. Each height sensor 340 is preferably supported adjacent one of the individual air springs and is also in communication with an electronic control unit (ECU) 342, such as by a control line 343. Additionally, an end-of-travel signal can be output by the height sensors indicating that one of the extreme positions, such as fully extended or fully compressed, for example, of the associated air spring has been reached or is being approached. Alternately, end-of-travel data can be determined by the ECU based upon a comparison of the signal from the height detector with known end-of-travel values stored within the ECU. ECU 342 is shown in FIG. 11 as being connected to an optional service switch 345 by control line 346 for selectively actuating the hydraulic jacks that are optionally provided on many trailerable RVs. Optionally, the switch can also include ON and/or OFF positions (FIG. 21) for the automatic leveling system used during operation of the vehicle. ECU 342 also is connected to a height switch 349 by a control line 350 and to a pair of indicating lights 355 and 356 by control lines 357 and 358, respectively. Height switch 349 can optionally be a multi-position height selection switch for use when the vehicle is selectively operable at a plurality of heights. ECU 342 also is operatively connected to the individual air spring control valves in valve control unit 325 by a plurality of control lines, indicated collectively at 361. As such, ECU 342 is adapted to selectively actuate one or more of the plurality of valves. It will be appreciated that any suitable speed or movement indicating device can be operatively connected to the ECU.

Many of the above-described components and manner of use are standard on many vehicle air suspension systems used for RVs and trailers to provide a multi-position leveling system and desired ride characteristic for the vehicle. Additionally, it will be appreciated that communications to and from the various devices and components of the vehicle, such as ECU 342, and height switch 349, for example, can be transmitted in any suitable manner. For example, each of the devices and components can be hard-wired to one another as prescribed by each of the various systems operative on the vehicle, with the signals communicated between the devices and components along the individual wires. As an example, if five different systems of the vehicle rely upon a signal from the accelerometer, five different wires may be interconnected to the accelerometer to provide the signal output by the accelerometer to each of the systems directly. However, many vehicles now include a CAN bus communication system that networks the various devices and components together. Such CAN bus communications systems are well known and commonly used. These systems can include a standalone controller or alternately be integrated into another controller of the vehicle, such as ECU 342, for example. One example of a suitable standard or protocol for such systems is SAE J1939. Though, it will be appreciated that a variety of other protocols exist and could alternately be used, such as CANOpen and DeviceNET, for example. One advantage of using a CAN bus communication system is that the actual physical wiring of the vehicle is greatly simplified. Another advantage is that the addition of a new device and/or system can be accomplished without significant physical modification of the vehicle. For example, the new system can be added to the vehicle simply by suitably mounting a new device on the vehicle, placing the device into communication with the CAN bus communication system, and making any attendant software and/or firmware modifications to the existing devices and/or components. Once installed, the new system can send and receive any other signals, information and/or data through the CAN bus communication system to operate the newly added system.

In accordance with the disclosure, an alignment sensor or level detection device, which is indicated generally at 365 and shown diagrammatically in FIGS. 16-18, is mounted on or operatively connected to vehicle chassis 304. Device 365 provides an alignment signal to ECU 342 through a control line 366. The alignment signal is indicative of the orientation of the vehicle chassis. Level detection device 365 can be of any suitable type of apparatus, such as an accelerometer, tilt sensor, gyroscopic sensor, and a transducer or other device that can detect the position, orientation or amount of tilt of a structural body and provide a signal, such as a relative voltage or current, as to the approximate position, orientation or amount of tilt of the structural body associated therewith. One particular type of level detection device is a dual-axis accelerometer manufactured by Memsic, Inc. of North Andover, Mass., identified as model MXR299ML. This sensor operates on a thermal principle, generating a signal, such as an output voltage, for example, for both the X-axis and Y-axis that varies according to the angular orientation of the sensor. Accelerometer 365 provides an analog or digital value or signal that is dependent upon the tilt or out of level of the vehicle chassis upon which the sensor is supported. This signal is supplied to ECU 342 through line 366. Accelerometer 365 can be attached to any part of the vehicle chassis. For example, the accelerometer could be secured to a portion of a frame, such as a cross beam, or to a portion of the body, such as a roof, side wall or floor. Additionally, the accelerometer can optionally be mounted centrally on the vehicle chassis. However, central mounting is not required.

Thus, in accordance with one of the features of the disclosure, a typical air suspension system for a vehicle as described above, is utilized without material modifications thereto with the exception of incorporating an alignment sensor or level detection device 365 that is operationally connected to ECU 342, in combination with the appropriate software utilized by ECU 342, to provide the operational features set forth in FIGS. 12-15, and further discussed below.

FIG. 21 represents a type of control panel 370, similar to the one illustrated in FIG. 8, which can be located on the dashboard of the vehicle for controlling both the ride suspension system for the vehicle during the dynamic operation thereof as well as the horizon leveling system of the present disclosure. The panel includes height switch 349 that controls the usual ride leveling system for the vehicle, indicating lights 355 and 356, the service switch 345, and a horizon leveling switch 372 that is connected to ECU 342 by a control line 373 (FIG. 11). An indication light 374 is connected to ECU 342 by a control line 369. Service switch 345 will be moved to one of three positions as shown in FIG. 21. The switch position can be illuminated by back lighting to indicate the selected position. If desired, panel could be a touch screen which would eliminate the toggle or rocker switches discussed above.

In accordance with one of the features of the disclosure, an artificial level position or horizon is indicated schematically by dot-dash line 371 (FIGS. 16, 17 and 19). This artificial horizon is programmed into ECU 342 as the predetermined datum. The predetermined datum is an imaginary reference plane that the system uses to align the vehicle chassis irrespective of the orientation of the axles, wheels of the vehicle or the supporting ground. Though line 371 is shown in FIGS. 16, 17 and 19 as being substantially horizontal, it will be appreciated that line 371 could be disposed in any desired orientation as established hereinbefore.

As illustrated in FIGS. 16 and 18, the towing configuration includes a towing vehicle 500 and a trailerable vehicle 502, such as a camper, etc. The towing vehicle 500 includes wheels 303 and a ball hitch 506. The towed vehicle 502 includes a ball hitch receptacle associated with a tongue 504, wheels 303, a rear axle 312, and a two-corner horizon leveling system. The two-corner horizon leveling system includes, in part, accelerometer 365, rear corner air spring members (FIG. 17) including end members 315 and 316, and flexible sleeves 317. FIG. 18 further illustrates a plan view of the towed vehicle.

According to another exemplary embodiment, as illustrated in FIGS. 19 and 20, the two-corner horizon leveling system can also be applied to a vehicle, such as a pick-up truck 600, which includes a two-corner air suspension system associated with the rear axle 312 and coil springs 602, or other type of conventional spring, operatively fixed to the front axle 311 and supporting the front of vehicle 600.

The steps for carrying out one embodiment of the present disclosure are illustrated in FIGS. 12 and 13, with a second embodiment being illustrated in FIGS. 14 and 15, by the flow charts contained therein.

Referring to FIG. 12, substantively, the first embodiment operates by the execution of program instructions by the ECU 342, the program instructions following the logic illustrated in FIG. 12.

Initially, the program starts 400, then the program proceeds to block 402, where the lateral axis of the two-corner air suspension vehicle is adjusted laterally by inflating or deflating one of the air springs until the desired latitudinal attitude is obtained.

Next, at block 403, the program determines if the longitudinal axis associated with the vehicle chassis is at the desired attitude. In the event the longitudinal axis is at the desired attitude, the program proceeds to block 408. In the event the longitudinal axis is not at the desired attitude, the program proceeds to block 404.

Next, at block 404, the program executes instructions to adjust the longitudinal axis to the desired attitude by inflating or deflating both of the rear two-corner air springs equally until the desired attitude is obtained.

Next, at block 406, the program determines if the lateral axis associated with the vehicle chassis is still at the desired attitude. If the lateral axis is properly aligned with the latitudinal component of the artificial horizon, the program ends at block 408. If the lateral axis is not properly aligned with the latitudinal component of the artificial horizon, the program returns to block 402 to adjust the lateral axis as previously discussed.

Referring to FIG. 13, a more detailed method of operation for a towed vehicle, i.e. trailer including a two-corner air suspension system, is now described. The vehicle operator, after the vehicle comes to a stop in an area such as a parking lot, campground, or the like, will actuate the horizon leveling system by actuating control switch 372 located on panel 370 in a compartment of the towed vehicle, as indicated by block 375 (FIG. 13A). In one preferred arrangement, this is done by depressing and holding control switch 372 for a predetermined period of time. A similar button hold can also be used to disengage the system. Thus, the opportunity for inadvertently initiating (or alternately, disengaging) the system, such as by bumping the switch, for example, is minimized. One example of a suitable duration for holding the switch in the depressed position is from about 3 to about 10 seconds and preferably about 4 seconds.

ECU 342 initially determines whether the vehicle chassis is aligned with the predetermined datum at block 377 by comparing the signals received from accelerometer 365 with respect to the artificial horizon 371 preset in ECU 342. If the vehicle floor or other reference plane is within an acceptable range on either side of artificial horizon 371 the ECU will send a signal and actuate indicator light 374, as represented by block 378, which will visually advise the operator that the vehicle is properly aligned. If the ECU senses that the vehicle chassis is out of alignment with the predetermined datum, it will then determine if the magnitude that the vehicle chassis is out of alignment is within the capability of the system to correct at block 379. If outside the capability of the system, it will send a signal to the operator, such as an audible tone or a flashing light 374, as shown by block 380, which immediately advises the operator that the vehicle is excessively uneven and that the suspension system will not be able to sufficiently compensate for the uneven terrain on which the vehicle is currently parked. The driver can then reposition the vehicle at that location or go to a different, more level location. If the out-of-level signal generated by accelerometer 365 is within the capability of the system to correct, the ECU will then proceed to block 381 where it will detect which corner of the vehicle is above artificial horizon 371, that is, right rear corner or left rear corner, as shown in FIG. 18.

One example of performing block 379 was previously described and is shown in FIG. 9. This performing block 379 includes a block 379A of providing end-of-travel data, such as from a height sensor, for example, indicative of one of the extreme positions of an air spring. Block 379 can also include a block 379B of storing the end-of-travel data in an ECU, for example. Block 379 can further include a block 379C of acquiring a signal indicative of the orientation of the vehicle chassis, such as from a height detector or an alignment sensor, for example. Block 379 can include still a further block 379D of comparing the signal indicative of orientation to the stored end-of-travel data. Still a further block 379E of determining if any difference between the signal and the end-of-travel data exceeds a predetermined value can be included in performing block 379. Another block 379F of selectively operating the control device to discontinue pressurized fluid flow if the predetermined value is exceeded can also be included in block 379.

Upon determining at block 381 which is the high corner of the vehicle, a determination then is made at block 382 (assuming for the purpose of this description that the right rear corner was determined to be the high corner) as to whether the amount of unevenness is within the capability of the suspension system to correct. If a determination is made that the right rear corner can be lowered sufficiently at block 382, a signal is then sent to block 383 to lower the right rear corner until the latitudinal axis of the vehicle is aligned with the latitudinal component of the predetermined datum representing the artificial horizon.

If the right corner 362 cannot be lowered sufficiently, block 388 (FIG. 13B) determines if the opposite corner can be raised sufficiently to compensate for the unevenness. If not, block 389 flashes indicating light 374 alerting the driver that the system is still checking if the proper alignment can be achieved. If the left corner can be raised sufficiently, block 390 raises the left rear corner to properly align the vehicle and proceeds to block 700.

After the vehicle chassis has been latitudinally aligned with the predetermined datum, block 700 determines if the longitudinal axis of the chassis is out of alignment with the predetermined datum. If block 700 determines the longitudinal axis of the chassis is properly aligned with the predetermined datum, the program returns to perform block 377, indicating proper alignment has been achieved and the appropriate signal is sent to light 374 via block 378 (FIG. 13A) and a timer circuit represented by block 392 which initiates monitoring and controlling of the chassis alignment after a preset time period such as one, two, etc. hours.

It is understood that if the left rear corner 363 of the vehicle is determined by block 381 to be the high corner, the same procedure is performed as discussed above for the right corner.

In the event block 700 determines the longitudinal axis of the chassis is out of alignment with the predetermined datum, the program proceeds to block 384 to determine if the front is high or the rear is high. Assuming it is determined the rear of the chassis is high, the program proceeds to block 385 to determine if the air springs can be lowered a sufficient distance. If they cannot be lowered a sufficient distance, then block 389 is performed which indicates longitudinal leveling cannot be achieved by performing block 391 which flashes light 374. If the air springs can be lowered a sufficient distance to longitudinally align the vehicle chassis, block 386 performs equal lowering of the rear corners to provide longitudinal alignment. Then the program returns to perform block 377, indicating proper alignment has been achieved and the appropriate signal is sent to light 374 via block 378 (FIG. 13A) and a timer circuit represented by block 392 initiates monitoring and controlling of the chassis alignment after a preset time period such as one, two, etc. hours.

Also, if the front end is determined to be high at block 384, the same procedure is performed for raising the rear end as discussed above for lowering the rear end except the air springs are equally inflated.

Specifically, block 387 determines if the air springs can be raised a sufficient distance. If they cannot be raised a sufficient distance, then block 389 is performed which indicates longitudinal leveling cannot be achieved by performing block 391. If the air springs can be raised a sufficient distance to longitudinally align the vehicle chassis, block 393 performs equal raising of the rear corners to provide longitudinal alignment. Then, the program returns to perform block 377, indicating proper alignment has been achieved and the appropriate signal is sent to light 374 via block 378 (FIG. 13A) and a timer circuit represented by block 392 initiates monitoring and controlling of the chassis alignment after a preset time period such as one, two, etc., hours.

According to one exemplary embodiment, the ECU initially determines, depending upon the reading received from level indicating device 365, whether the amount of unevenness is too great to be compensated for by the system and to initially alert the operator to relocate the vehicle. This avoids the need to attempt the alignment of the vehicle body by actuation of the appropriate air springs only then to find out that the vehicle body cannot be aligned due to the excessive unevenness of the terrain. This saves time and unnecessary manipulation of the air spring components, fluid supplies, etc.

ECU 342 preferably includes a standard microchip that can be programmed by one skilled in the art to provide those features discussed above and shown in FIGS. 12-15.

Described hereto with reference to FIGS. 12 and 13 is a method of operating a two-corner horizon leveling associated with a trailerable vehicle, such as a camper. In addition, the described method and system can also be applied to a two-axle vehicle, such as a pick-up truck, which includes an air suspension system to control the height of the rear of the pick-up truck and a spring or leaf type spring arrangement associated with the front axle.

Described now is a system and method of operating a two-corner horizon leveling system associated with a trailerable vehicle, where the trailer air suspension system ECU communicates with the towing vehicle to provide further longitudinal axis alignment of the trailer chassis with an artificial horizon. This disclosed method is shown in FIGS. 14-15 and is applied to a towing configuration as illustrated in FIG. 16.

With reference to FIG. 14, substantively, this method operates by the execution of program instructions by the ECU 342, the program instructions following the logic illustrated in FIG. 14.

Initially, the program starts 450, then the program proceeds to block 452, where the lateral axis of the two-corner air suspension trailer is adjusted laterally by inflating or deflating one of the trailer rear air springs until the desired latitudinal attitude is obtained.

Next, at block 453, the program determines if the longitudinal axis associated with the trailer is at the desired attitude. In the event the longitudinal axis is at the desired attitude, the program proceeds to block 458. In the event the longitudinal axis is not at the desired attitude, the program proceeds to block 454.

Next, at block 454, the program executes instructions to adjust the longitudinal axis of the trailer to the desired attitude by inflating or deflating both of the rear two-corner air springs equally and/or controlling the towing vehicle suspension system to raise or lower the front of the trailer.

Next, at block 456, the program determines if the lateral axis associated with the trailer chassis is still at the desired attitude. If the lateral axis is properly aligned with the latitudinal component of the artificial horizon, the program ends at block 458. If the lateral axis is not properly aligned with the latitudinal component of the artificial horizon, the program returns to block 402 to adjust the lateral axis as previously discussed.

With reference to FIG. 15, now described is a more detailed method of operating a two-corner horizon leveling system including the control of an associated towing vehicle suspension system.

Notably, the initial operation is just as the method described with reference to FIGS. 13A and 13B. Specifically, the method adjusts the lateral axis of the trailer to properly align with the latitudinal component of the artificial horizon by inflating or deflating the trailer right rear and left rear air springs until the desired lateral attitude is obtained. Then, the method determines if the longitudinal axis of the chassis is misaligned at block 700. However, unlike the method described with reference to FIGS. 12 and 13, as illustrated in FIG. 15, in the event it is determined at block 700 that the longitudinal axis of the trailer chassis is misaligned and the two-corner air suspension system associated with the trailer cannot lower or raise the rear corners to properly longitudinally align the trailer, blocks 702, 704, 706 and/or 708 perform the raising or lowering of the towing vehicle hitch to longitudinally align the trailer.

Specifically, if block 384 determines the rear of the trailer is high, relative to the artificial horizon predetermined datum, then block 385 determines if the two-corner air suspension system operatively associated with the trailer can lower the rear of the trailer chassis to properly align the trailer chassis with the longitudinal axis associated with the artificial horizon.

In the event the trailer air suspension system cannot longitudinally align the trailer chassis, block 706 determines if the towing vehicle hitch can be raised indirectly as a result of raising the towing vehicle rear suspension to longitudinally align the trailer chassis. If the towing vehicle hitch can be raised, block 708 raises the hitch to longitudinally align the trailer chassis with the longitudinal axis associated with the artificial horizon.

In the event block 384 determines the rear of the trailer is low, relative to the artificial horizon predetermined datum, then block 387 determines if the two-corner air suspension system operatively associated with the trailer can raise the rear of the trailer chassis with the longitudinal axis associated with the artificial horizon.

In the event the trailer air suspension system cannot longitudinally align the trailer chassis, block 702 determines if the towing vehicle hitch can be lowered indirectly as a result of lowering the towing vehicle rear suspension to longitudinally align the trailer chassis. If the towing vehicle hitch can be lowered, block 704 lowers the hitch to longitudinally align the trailer chassis with the longitudinal axis associated with the artificial horizon.

It is to be understood that the method described with reference to FIG. 15 can be modified to include other features previously discussed. Specifically, but not limited to, end of travel data associated with the towing vehicle can be utilized to determine if the towing vehicle suspension system can provide the necessary longitudinal alignment of the trailer chassis. In addition, the methods of FIGS. 14 and 15 can include partial longitudinal alignment of the trailer chassis using the towing vehicle's suspension system. In other words, the towing vehicle partially aligns the longitudinal axis of the trailer by raising or lowering the hitch, and the trailer two-corner air suspension system provides the additional longitudinal alignment required.

In order for the method of FIG. 15 to be executed, the trailer ECU will communicate with the fluid suspension system ECU of the towing vehicle by means of a hardwire connection, i.e. connector, or wireless connection. Alternatively, the ECU of the trailer two-corner air suspension system could directly control the fluid suspension system hardware associated with the towing vehicle.

As another alternative, in the event the towing vehicle ECU and trailer ECU cannot communicate, the trailer ECU could instruct an operator, by means of the trailer mounted display, to manually raise or lower the towing vehicle rear suspension. Notably, controlling the longitudinal alignment of the trailer chassis by raising/lowering the towing vehicle rear suspension may be provided as an option to moving the trailer chassis to a more level area.

While the disclosure has been described with reference to the foregoing embodiments and considerable emphasis has been placed herein on the structures and structural interrelationships between the component parts of the embodiments disclosed, it will be appreciated that other embodiments of the disclosure can be made and that many changes can be made in the embodiments illustrated and described without departing from the principles of the disclosure. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. Accordingly, it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the present disclosure and not as a limitation. As such, it is intended that the disclosure be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims. 

1. A method of positioning a vehicle chassis of a vehicle in approximate alignment with a predetermined datum, the vehicle chassis including a first longitudinal end adapted to be pivotally connected to a substantially fixed point and a second longitudinal end, the vehicle including at least one axle associated with the second longitudinal end and a two-corner fluid suspension system including a first corner fluid suspension member disposed between the axle and a first corner associated with the second longitudinal end of the chassis, a second corner fluid suspension member disposed between the axle and a second corner associated with the second longitudinal end of the chassis, a fluid control device, a pressurized fluid source in fluid communication with the fluid suspension members through the fluid control device, an exhaust passage in fluid communication with the fluid suspension members through the fluid control device, an alignment sensor supported on the chassis for outputting a signal indicative of the lateral orientation of the chassis and the longitudinal orientation of the chassis, and an electronic control unit operatively associated with the control of the first corner fluid suspension member and the second corner fluid suspension member, the method comprising: a) acquiring the alignment signal generated by the alignment sensor and comparing the alignment signal to the predetermined datum to determine if one or more of the lateral and longitudinal orientation of the chassis is misaligned relative to the predetermined datum and, if the chassis is misaligned, performing the method comprising: b) controlling one or more of the first corner suspension member and the second corner suspension member to laterally align the chassis with a lateral component of the predetermined datum; c) controlling the first corner suspension member and the second corner suspension member to longitudinally align the chassis with a longitudinal component of the predetermined datum, the first corner suspension member and the second corner suspension member controlled to be inflated an equal distance or deflated an equal distance until the chassis is longitudinally aligned with the longitudinal component of the predetermined datum; and d) acquiring the alignment signal generated by the alignment sensor and comparing said alignment signal to the predetermined datum to determine if the lateral orientation of the chassis is aligned with the predetermined datum, and if the chassis is misaligned, repeating steps b), c) and d).
 2. The method of positioning a vehicle chassis of a vehicle in approximate alignment with a predetermined datum according to claim 1, step c) comprising: determining whether one of the first corner suspension member and the second corner suspension member can be lowered a sufficient distance to laterally align the chassis with the lateral component of the predetermined datum; if one of the corner suspension members can be lowered the sufficient distance, selectively operating the fluid control device to permit fluid communication between the exhaust passage and the respective corner suspension member until the chassis is approximately laterally aligned with the lateral component of the predetermined datum; and if one of the corner suspension members cannot be lowered the sufficient distance, then selectively operating the fluid control device to permit fluid communication between the pressurized fluid source and one of the corner suspension members until the chassis is approximately laterally aligned with the lateral component of the predetermined datum.
 3. The method of positioning a vehicle chassis of a vehicle in approximate alignment with a predetermined datum according to claim 1, further comprising: determining whether one of the corner suspension members is capable of being raised the sufficient distance to approximately laterally align the chassis with the lateral component of the predetermined datum.
 4. The method of positioning a vehicle chassis of a vehicle in approximate alignment with a predetermined datum according to claim 3, wherein one of the corner suspension members is incapable of being lowered the sufficient distance to approximately laterally align the chassis with the lateral component of the predetermined datum and the other corner suspension member is incapable of being raised the sufficient distance to approximately laterally align the chassis with the lateral component of the predetermined datum, the method further comprising communicating to an associated operator that the fluid suspension system is incapable of aligning the chassis with the predetermined datum.
 5. The method of positioning a vehicle chassis of a vehicle in approximate alignment with a predetermined datum according to claim 1, further comprising communicating to an associated operator that the chassis is in approximate alignment with the predetermined datum.
 6. The method of positioning a vehicle chassis of a vehicle in approximate alignment with a predetermined datum according to claim 1, further comprising calibrating the alignment sensor prior to step a).
 7. The method of positioning a vehicle chassis of a vehicle in approximate alignment with a predetermined datum according to claim 6, wherein calibrating the alignment sensor includes positioning a wall of the chassis in substantial alignment with the predetermined datum, acquiring an initial alignment signal from the alignment sensor with the chassis in substantial alignment with the predetermined datum, and storing data having a relation to the initial alignment signal in the electronic control unit as the alignment data.
 8. The method of positioning a vehicle chassis of a vehicle in approximate alignment with a predetermined datum according to claim 1, wherein the vehicle is a trailer and the fixed point is a hitch associated with a second vehicle.
 9. The method of positioning a vehicle chassis of a vehicle in approximate alignment with a predetermined datum according to claim 1, wherein the vehicle includes at least one axle associated with the first longitudinal end and substantially fixed suspension members between the axle associated with the first longitudinal end provide the pivotal connection to a substantially fixed point.
 10. The method of positioning a vehicle chassis of a vehicle in approximate alignment with a predetermined datum according to claim 1, wherein the vehicle chassis is pivotally connected to a substantially fixed point associated with a second vehicle, the second vehicle including a fluid suspension system operatively connected to the electronic control unit operatively associated with the control of the first corner fluid suspension member and the second corner fluid suspension member, the method further comprising: lowering or raising the fluid suspension system associated with the second vehicle to longitudinally align the vehicle chassis.
 11. The method of positioning a vehicle chassis of a vehicle in approximate alignment with a predetermined datum according to claim 10, further comprising: longitudinally aligning the vehicle chassis by controlling the second vehicle fluid suspension system and controlling the first and second corner suspension members associated with the vehicle.
 12. A suspension system for supporting an associated chassis of an associated vehicle in approximate alignment with a predetermined datum, the vehicle chassis including a first longitudinal end adapted to be pivotally connected to a substantially fixed point and a second longitudinal end, and the associated vehicle including at least one axle supporting the associated chassis substantially near the second longitudinal end, the suspension system comprising: a first corner fluid suspension member disposed between the axle and a first corner associated with the second longitudinal end of the chassis; a second corner fluid suspension member disposed between the axle and a second corner associated with the second longitudinal end of the chassis; a fluid control device; a pressurized fluid source in fluid communication with the fluid suspension members through the fluid control device; an exhaust passage in fluid communication with the fluid suspension members through the fluid control device; an alignment sensor supported on the chassis for outputting a signal indicative of the lateral orientation of the chassis and the longitudinal orientation of the chassis; and an electronic control unit operatively associated with the control of the first corner fluid suspension member and the second corner fluid suspension member, the electronic control unit configured to execute instructions to perform a method of positioning the vehicle chassis of the vehicle in approximate alignment with the predetermined datum comprising: a) acquiring the alignment signal generated by the alignment sensor and comparing the alignment signal to the predetermined datum to determine if one or more of the lateral and longitudinal orientation of the chassis is misaligned relative to the predetermined datum and, if the chassis is misaligned, performing the method comprising: b) controlling one or more of the first corner suspension member and the second corner suspension member to laterally align the chassis with a lateral component of the predetermined datum; c) controlling the first corner suspension member and the second corner suspension member to longitudinally align the chassis with a longitudinal component of the predetermined datum, the first corner suspension member and the second corner suspension member controlled to be inflated an equal distance or deflated an equal distance until the chassis is longitudinally aligned with the longitudinal component of the predetermined datum; and d) acquiring the alignment signal generated by the alignment sensor and comparing said alignment signal to the predetermined datum to determine if the lateral orientation of the chassis is aligned with the predetermined datum, and if the chassis is misaligned, repeating steps b), c) and d).
 13. The suspension system according to claim 12, step c) comprising: determining whether one of the first corner suspension member and the second corner suspension member can be lowered a sufficient distance to laterally align the chassis with the lateral component of the predetermined datum; if one of the corner suspension members can be lowered the sufficient distance, selectively operating the fluid control device to permit fluid communication between the exhaust passage and the respective corner suspension member until the chassis is approximately laterally aligned with the lateral component of the predetermined datum; and if one of the corner suspension members cannot be lowered the sufficient distance, then selectively operating the fluid control device to permit fluid communication between the pressurized fluid source and one of the corner suspension members until the chassis is approximately laterally aligned with the lateral component of the predetermined datum.
 14. The suspension system according to claim 12, wherein the method further comprises: determining whether one of the corner suspension members is capable of being raised the sufficient distance to approximately laterally align the chassis with the lateral component of the predetermined datum.
 15. The suspension system according to claim 14, wherein one of the corner suspension members is incapable of being lowered the sufficient distance to approximately laterally align the chassis with the lateral component of the predetermined datum and the other corner suspension member is incapable of being raised the sufficient distance to approximately laterally align the chassis with the lateral component of the predetermined datum, the method further comprising communicating to an associated operator that the fluid suspension system is incapable of aligning the chassis with the predetermined datum.
 16. The suspension system according to claim 12, the method further comprising communicating to an associated operator that the chassis is in approximate alignment with the predetermined datum.
 17. The suspension system according to claim 16, the method further comprising calibrating the alignment sensor prior to step a).
 18. The suspension system according to claim 17, wherein calibrating the alignment sensor includes positioning a wall of the chassis in substantial alignment with the predetermined datum, acquiring an initial alignment signal from the alignment sensor with the chassis in substantial alignment with the predetermined datum, and storing data having a relation to the initial alignment signal in the electronic control unit as the alignment data.
 19. The suspension system according to claim 12, wherein the vehicle is a trailer and the fixed point is a hitch associated with a second vehicle.
 20. The suspension system according to claim 12, wherein the vehicle includes at least one axle associated with the first longitudinal end and substantially fixed suspension members between the axle associated with the first longitudinal end provides the pivotal connection to a substantially fixed point.
 21. The suspension system according to claim 12, the method further comprising: lowering or raising the fluid suspension system associated with the second vehicle to longitudinally align the vehicle chassis.
 22. The suspension system according to claim 21, the method further comprising: longitudinally aligning the vehicle chassis by controlling the second vehicle fluid suspension system and controlling the first and second corner suspension members associated with the vehicle.
 23. A computer program product, that when executed, causes a computer to execute instructions to perform a method of positioning a vehicle chassis of a vehicle in approximate alignment with a predetermined datum, the vehicle chassis including a first longitudinal end adapted to be pivotally connected to a substantially fixed point and a second longitudinal end, the vehicle including at least one axle associated with the second longitudinal end and a two-corner fluid suspension system including a first corner fluid suspension member disposed between the axle and a first corner associated with the second longitudinal end of the chassis, a second corner fluid suspension member disposed between the axle and a second corner associated with the second longitudinal end of the chassis, a fluid control device, a pressurized fluid source in fluid communication with the fluid suspension members through the fluid control device, an exhaust passage in fluid communication with the fluid suspension members through the fluid control device, an alignment sensor supported on the chassis for outputting a signal indicative of the lateral orientation of the chassis and the longitudinal orientation of the chassis, and an electronic control unit operatively associated with the control of the first corner fluid suspension member and the second corner fluid suspension member, the method comprising: a) acquiring the alignment signal generated by the alignment sensor and comparing the alignment signal to the predetermined datum to determine if one or more of the lateral and longitudinal orientation of the chassis is misaligned relative to the predetermined datum and, if the chassis is misaligned, performing the method comprising: b) controlling one or more of the first corner suspension member and the second corner suspension member to laterally align the chassis with a lateral component of the predetermined datum; c) controlling the first corner suspension member and the second corner suspension member to longitudinally align the chassis with a longitudinal component of the predetermined datum, the first corner suspension member and the second corner suspension member controlled to be inflated an equal distance or deflated an equal distance until the chassis is longitudinally aligned with the longitudinal component of the predetermined datum; and d) acquiring the alignment signal generated by the alignment sensor and comparing said alignment signal to the predetermined datum to determine if the lateral orientation of the chassis is aligned with the predetermined datum, and if the chassis is misaligned, repeating steps b), c) and d).
 24. The computer program product according to claim 23, step c) comprising: determining whether one of the first corner suspension member and the second corner suspension member can be lowered a sufficient distance to laterally align the chassis with the lateral component of the predetermined datum; if one of the corner suspension members can be lowered the sufficient distance, selectively operating the fluid control device to permit fluid communication between the exhaust passage and the respective corner suspension member until the chassis is approximately laterally aligned with the lateral component of the predetermined datum; and if one of the corner suspension members cannot be lowered the sufficient distance, then selectively operating the fluid control device to permit fluid communication between the pressurized fluid source and one of the corner suspension members until the chassis is approximately laterally aligned with the lateral component of the predetermined datum.
 25. The computer program product according to claim 23, the method further comprising: determining whether one of the corner suspension members is capable of being raised the sufficient distance to approximately laterally align the chassis with the lateral component of the predetermined datum. 